Semi-submersible pipelaying vessel having an improved pipelaying path

Abstract

A semi-submersible pipelaying vessel has an improved configuration and structure for laying pipe wherein the pipeline path extends along a port or starboard side of the vessel. The pipeline path passes through the upper deck member of the vessel and then through a supporting column member of the vessel. A cantilevered overhang or deck member extension is not required. The pipe is supported along the pipeline path by a plurality of pipeline supports for providing the pipe at the stern of the vessel with the correct inclination with respect to the water surface. The slotted column advantageously provides protection for the pipeline below the deck level with respect to lateral wave action forces and added vessel stability and/or work area efficiency.

What is claimed is: 
     
       1. A semi-submersible pipeline laying vessel comprising an upper deck member having a longitudinally directed pass-through opening,   at least one lower submersible buoyancy member,   a plurality of bow-to-stern spaced support members connected between said buoyancy member and said deck member for supporting said deck member in an upward, spaced-apart relationship with said buoyancy member, at least one of said support members at a stern portion of the vessel having a longitudinally directed vertical cut-away section extending through an interior section thereof to define port and starboard portions of said at least one support member, and said section being aligned with said deck opening,   a pipelaying means partially supported by and above said deck member for fabricating a pipeline from a plurality of pipelengths, said pipelaying means comprising a plurality of operating stations arranged along a pipeline path, said path extending longitudinally of said vessel from an above deck position to a below deck position at the stern of said vessel, and in alignment with and passing through said deck pass-through opening and said one support vertical cut-away section,   whereby said pipeline is at least partially shielded from port and starboard directed lateral wave action forces by said one support when said pipeline is below the level of said deck member.   
     
     
       2. The vessel of claim 1 wherein said pipelaying means comprises means supported by said at least one support member.   
     
     
       3. The vessel of claim 1 wherein said deck opening is positioned toward the stern of the vessel. 
     
     
       4. In a semi-submersible pipeline laying vessel having an upper deck member,   at least two lower submersible buoyancy members,   a plurality of bow-to-stern spaced support members connected between said buoyancy member and said deck member for supporting said deck member in an upward, spaced-apart relationship with said buoyancy member, and   a pipelaying means at least partially supported by and above said deck member for fabricating a pipeline from a plurality of pipelengths, said pipelaying means defining a pipeline path,   the improvement comprising   at least one support member at the stern of the vessel having a vertical cut-away section passing through an interior portion thereof to define port and starboard portions of said at least one support member,   the deck member having a pass-through opening aligned with said cut-away section, and   said pipelaying means having means for directing said pipeline path through said pass-through section and through said cut-away section,   whereby said pipeline is at least partially shielded from port and starboard directed lateral wave action forces by said one support member when said pipeline is below the level of said deck member.   
     
     
       5. The pipeline laying vessel of claim 4 wherein each said one support member has a horizontal cross-sectional area at least equal to the horizontal cross section of each said other support member. 
     
     
       6. The pipeline laying vessel of claim 5 wherein each said one support member has a longitudinal length greater than the longitudinal length of each said other support member. 
     
     
       7. A semi-submersible pipeline laying vessel comprising an upper deck member having a longitudinally directed pass-through opening,   at least two lower submersible, laterally spaced buoyancy members,   a plurality of bow-to-stern spaced support members connected between said buoyancy members and said deck member for supporting said deck member in an upward spaced-apart relationship with said buoyancy member, at least one of said support members at a stern portion of the vessel having a longitudinally directed vertical cut-away section aligned with said deck opening, and extending substantially the entire height of the support between the deck and the buoyancy members and dividing said one support into port and starboard support subsections,   a pipeline means partially supported by and above said deck member for fabricating a pipeline from a plurality of pipe-lengths, said pipeline means comprising a plurality of operating stations arranged from a pipelane path, said path extending longitudinally of said vessel from an above deck position to a below deck position at the stern of the vessel, and in alignment with and passing through said deck and said one support vertical cut-away section,   whereby said pipeline path be adjusted in a vertical direction and said pipeline is at least partially shielded from lateral wave action forces by one support when said pipeline is below the level of said deck member.   
     
     
       8. The vessel of claim 7 wherein each support member has a preselected buoyancy capacity and said at least one support member has a buoyancy capacity at least equal to the buoyancy of the other support members.